Electrochemical device and electronic device

Abstract

An electrochemical device includes a positive electrode plate which includes a positive active material layer and a negative electrode plate which includes a negative current collector, a first negative active material layer, and a second negative active material layer. In a length direction, the first negative active material layer includes a first edge and a second edge opposite to the first edge. In the length direction, the second negative active material layer includes a third edge and a fourth edge opposite to the third edge. In the length direction, the positive active material layer includes a fifth edge and a sixth edge opposite to the fifth edge. The third edge protrudes beyond the first edge and the fifth edge in the length direction. A distance between the first edge and the fifth edge in the length direction of the negative electrode plate is less than 2 mm.

What is claimed is: 
     
         1 . An electrochemical device, comprising: a positive electrode plate and a negative electrode plate; wherein,
 the positive electrode plate comprises a positive active material layer;   the negative electrode plate comprises a negative current collector, a first negative active material layer, and a second negative active material layer; and the first negative active material layer is located between the negative current collector and the second negative active material layer;   in a length direction, the first negative active material layer comprises a first edge and a second edge opposite to the first edge; in the length direction, the second negative active material layer comprises a third edge and a fourth edge opposite to the third edge;   in the length direction, the positive active material layer comprises a fifth edge and a sixth edge opposite to the fifth edge;   in the length direction, the first edge, the third edge, and the fifth edge are located on a first side; and the second edge, the fourth edge, and the sixth edge are located on a second side; the first side being opposite to the second side;   the third edge protrudes beyond the first edge and the fifth edge in the length direction; and   a distance between the first edge and the fifth edge in the length direction is less than 2 mm.   
     
     
         2 . The electrochemical device according to  claim 1 , wherein
 the distance between the first edge and the fifth edge in the length direction is 0.   
     
     
         3 . The electrochemical device according to  claim 1 , wherein the fourth edge protrudes beyond the second edge and the sixth edge in the length direction. 
     
     
         4 . The electrochemical device according to  claim 3 , wherein a distance between the second edge and the sixth edge in the length direction is less than 2 mm. 
     
     
         5 . The electrochemical device according to  claim 4 , wherein the distance between the second edge and the sixth edge in the length direction is 0. 
     
     
         6 . The electrochemical device according to  claim 1 , wherein a distance between the third edge and the fifth edge in the length direction is 2 mm to 8 mm. 
     
     
         7 . The electrochemical device according to  claim 3 , wherein a distance between the fourth edge and the sixth edge in the length direction is 2 mm to 8 mm. 
     
     
         8 . The electrochemical device according to  claim 1 , wherein
 a gram capacity of a negative active material in the first negative active material layer is greater than a gram capacity of a negative active material in the second negative active material layer.   
     
     
         9 . The electrochemical device according to  claim 1 , satisfying at least one of the following conditions:
 (a) a resistivity of the second negative active material layer is less than a resistivity of the first negative active material layer; (b) a mass percentage of a conductive agent in the first negative active material layer is less than a mass percentage of a conductive agent in the second negative active material layer;   (c) a porosity of the first negative active material layer is less than a porosity of the second negative active material layer;   (d) the first negative active material layer and the second negative active material layer comprise: a negative active material coated with a modifier, and a coating amount of the negative active material in the first negative active material layer is less than a coating amount of the negative active material in the second negative active material layer;   (e) an average particle diameter of the negative active material in the first negative active material layer is greater than an average particle diameter of the negative active material in the second negative active material layer; or   (f) the first negative active material layer and the second negative active material layer comprise graphite, and a graphite orientation index in the first negative active material layer is greater than a graphite orientation index in the second negative active material layer.   
     
     
         10 . An electronic device, comprising an electrochemical device, the electrochemical device, comprising: a positive electrode plate and a negative electrode plate; wherein,
 the positive electrode plate comprises a positive active material layer;   the negative electrode plate comprises a negative current collector, a first negative active material layer, and a second negative active material layer; and the first negative active material layer is located between the negative current collector and the second negative active material layer;   in a length direction, the first negative active material layer comprises a first edge and a second edge opposite to the first edge; in the length direction, the second negative active material layer comprises a third edge and a fourth edge opposite to the third edge;   in the length direction, the positive active material layer comprises a fifth edge and a sixth edge opposite to the fifth edge;   in the length direction, the first edge, the third edge, and the fifth edge are located on a first side; and the second edge, the fourth edge, and the sixth edge are located on a second side; the first side being opposite to the second side;   the third edge protrudes beyond the first edge and the fifth edge in the length direction; and   a distance between the first edge and the fifth edge in the length direction is less than 2 mm.   
     
     
         11 . The electronic device according to  claim 10 , wherein
 the distance between the first edge and the fifth edge in the length direction is 0.   
     
     
         12 . The electronic device according to  claim 10 , wherein the fourth edge protrudes beyond the second edge and the sixth edge in the length direction. 
     
     
         13 . The electronic device according to  claim 12 , wherein a distance between the second edge and the sixth edge in the length direction is less than 2 mm. 
     
     
         14 . The electronic device according to  claim 13 , wherein the distance between the second edge and the sixth edge in the length direction is 0. 
     
     
         15 . The electronic device according to  claim 10 , wherein a distance between the third edge and the fifth edge in the length direction is 2 mm to 8 mm. 
     
     
         16 . The electronic device according to  claim 12 , wherein a distance between the fourth edge and the sixth edge in the length direction is 2 mm to 8 mm. 
     
     
         17 . The electronic device according to  claim 10 , wherein a gram capacity of a negative active material in the first negative active material layer is greater than a gram capacity of a negative active material in the second negative active material layer. 
     
     
         18 . The electronic device according to  claim 1 , satisfying at least one of the following conditions:
 (a) a resistivity of the second negative active material layer is less than a resistivity of the first negative active material layer; (b) a mass percentage of a conductive agent in the first negative active material layer is less than a mass percentage of a conductive agent in the second negative active material layer;   (c) a porosity of the first negative active material layer is less than a porosity of the second negative active material layer;   (d) the first negative active material layer and the second negative active material layer comprise: a negative active material coated with a modifier, and a coating amount of the negative active material in the first negative active material layer is less than a coating amount of the negative active material in the second negative active material layer;   (e) an average particle diameter of the negative active material in the first negative active material layer is greater than an average particle diameter of the negative active material in the second negative active material layer; or   (f) the first negative active material layer and the second negative active material layer comprise graphite, and a graphite orientation index in the first negative active material layer is greater than a graphite orientation index in the second negative active material layer.